The study proposes to delineate (a) cellular sites in human beings of earliest multiplication of varicella virus and (b) the use of a primate model infected with a varicella-like simian herpesvirus for directional clues relating to the pathogenesis of varicella. Aspects of the study depend on (c) optimal system(s) for recovering virus, and (d) the rescue of the infectious virion from an avid cell association. The primary objectives relate to epidemiologic and pathogenetic principles operative in human beings. Children exposed to varicella within hospital are candidates for these studies. In view of our past difficulties in recovering VZ virus from excretions in the naturally-occurring infection we plan to study pathogenetic pathways in macaque monkeys. A varicella-like disease has been recognized, and can be experimentally reproduced in monkeys.